Manufacture of zirconium tetrafluoride catalyst



Uiteai rates This invention relates to manufacture of catalyticmaterials particularly active in promoting reactions in which halogencompounds are reactants and/ or products. More specifically, theinvention is directed to methods for making zirconium fluoride catalystswhich are active in altering the halogen content of organic carboncompounds containing halogen.

Antimony fluoride and mixtures thereof with'antimony chloride have beenused in promoting e. g. fiuorination of aliphatic halides with HP tobring about substitution of halogen other than fluorine by fluorine.These operations, though commercially successful, are nonethelesscharacterized by certain disadvantages arising by reason ofcorrosiveness, liquid form, and high volatility of antimony halides, thelatter factor leading to substantial operational difiiculties. Aluminumchloride has been proposed for catalyzing disproportionation(redistribution of halogen among the molecules of compounds containingmore than one variety of halogen atom) but yields have not been as highas desired, and also aluminum chloride is limited with respect tooperation at high temperature by high volatility. For conductinghydrohalogenation (addition of hydrogen halide to a double bond toproduce saturation) or dehydrohalogenation (removal of hydrogen halidefrom adjoining carbon atoms to produce an unsaturated linkage),catalysts such as chromium trifluoride, gaseous free oxygen andactivated carbon have been proposed but such processes encounter thedisadvantage of necessity of high reaction temperature or undesirablylow conversion or, as in the case of the gaseous oxygen catalyst, lackof ease of manipulation and control.

General objects of this invention include development of methods forpreparing zirconium fluoride (ZI'F) catalytic materials which aresolids, which are effective in promoting certain types of reactionsinvolving alteration of the halogen (e. g. fluorine) content of organiccarbon halogen-containing compounds, such as fiuorination of halogenatedorganic compounds with HF, disproportionation, hydrohalogenation anddehydrohalogenation, and which are free of the disadvantages of liquidor gaseous catalysts, and which effect good yields and conversions ofsought-for products.

Zirconium tetrafluorides may be made for example in a liquid phaseoperation by reaction of zirconium tetrachloride and liquid hydrofluoricacid, or in a gas phase operation by HF gassing, at certain temperatureconditions, of zirconium tetrachloride. Investigations out of which thisinvention arises demonstrate thatzirconium tetrafluorides in generalpossess catalytic potentialities with regard to promotion of reactionsof the type above noted, and that catalytic properties of zirconiumtetrafluorides may vary mostly with regard to the nature of thezirconium tetrachloride starting material and to the manner in which thetetrachloride is converted to the tetrafluoride, and also to some lesserbut notable extent in certain instances as to the type of reaction whichthe zirconium tetrafluoride is employed to catalyze. The instantdevelopment work shows that there are significant differences as toactivity between the various zirconium tetrafluoride catalysts which maybe made by treatment of solid zirconium tetrachlorides with gaseous HF.The improvement afforded by the present invention are based largely onthe primary discovery that the catalytic activity tailed conditions toform a ZrF4 catalyst.

differences between various zirconium tetrafluoride catalysts which maybe made by gas phase methods are attributable primarily and to a majorextent to the nature of the zirconium chloride (herein intended todenote ZrCl4 and no other form of zirconium chloride) starting material,and probably secondarily to the nature or characteristics of theparticular procedures used to convert the zirconium tetrachloride to thetetrafluoride.

The only kind of zirconium chloride currently available commercially isin the form of a fine powder. Such a material may be gassed with HFunder substantially anhydrous and certain other conditions to convertthe ZrCLi to ZrF4. The resulting product has catalytic properties,andmay be used to catalyze some halogen exchange reactions in certaintypes of reactions with acceptable results. Procedural factors ofpractice of this invention involve gassing ofa certain ZrCl4 startingmaterial with anhydrous HF under particular hereinafter de- Although theexact reasons for differences between catalytic activity of ZrF4catalysts made from commercial ZrCl4 on the one hand and the ZrF4catalysts of this invention are not clearly known or understood, inaccordance with the invention, .it has been found that the use in theforegoing procedure of a certain ZrCl4 startingmaterial results-in theproduction of a ZrFicatalyst which is highly active inpromoting certainhalogen exchange reactions, particularly. fiuorination with HF.

Commercial zirconium tetrachloride is made in operations which involvechemically forming ZrClr at high temperatures substantially higher thanthe sublimation temperature of. solid ZrCl4, and the condensation ofZICM out of the resulting gas stream which contains ZrCl vapor, and arelatively large volume of other gases and 'vapors. Thus, themanufacturing process is such [that the ZI'Clel is deposited orcondensed out of its carrying gas stream and recovered in thecommercially available form of discrete particles of fine powderytexture. As distinguished from a line powder, the ZrC14 utilized asstarting material to make the ZrF4 catalysts of the invention may bedefinedin general as initially having been derived as a solid coherentmass, .e. g. as a solid coherent massive material formed as asolidsublimate.

More particularly, the ZrCli starting material which is subjected totreatment with gaseous hydrogen fluoride to produce the ZrFi catalystsof the instant improvements may be considered as material having beenformed by condensing, in a condensing zone, sublimed vapor of thesublimation of zirconium tetrachloride in .an anhydrous inert gaseousatmosphere under conditions to form anhydrous zirconium tetrafluoride inthe form of a solid coherent mass incrusted on and adhering to thecooling surfaces of the condensing zone.

Sublimation apparatus suitable for use to produce th Zl'CLi starting.material may comprise a metal heating pot or boiler provided with avalved inlet pipe for nitrogen or other inert gas opening into the gasspace of the pot, and with heating equipment adequate to raisetemperature in the pot high enough, e. g..300375 C., to vaporizezirconium. tetrachloride. The top of the boiler may be connected thru avapor line with a condenser equipped with suitable cooling means. Fheupper end of the condensing zone communicates with a valve controlledoverhead gas oiftake line which discharges to the atmosphere. Theofftake line may have associated therewith a manometer arranged toindicate gas pressure in the gas space in the boiler, in the condenserand in the connecting piping. Also, there may be connected to thedischarge line any suitable device, such as a water wash tube, fordetecting the presence of ZrClr in-the exit gas. 7 I i In accordancewith the invention, the best ZrCl4 t9 Patented Sept. 3, 1957 be used asstarting material is the solid substantially anhydrous ZrCl4 which isformed by condensing the' sublimed vapor of zirconium tetrachloride inan atmosphere consisting substantially of its own vapor. However,production of ZrClr sublimate in'thismanner may'prer 'sent somepractical difiiculties arising from non-feasibility of making andoperating sublimation. equipment which is effective to whollypreventinfiltration into the vapor spaces of the still and condenser ofsmall amounts of atmospheric air and its included'moisture. It haslbeenfound that the conditions needed forproduction of the herein ZrCl4'starting materials comprise the conjunctive relation of the formationofZrClr vapor. by the sublimation of solid ZI'C14 e. g; the commerciallyavailablejpowdery materiaL 'in which operation the ZrGli'vap'or' is notsubjected to relatively high temperature, i; e. maximum temperature ofvapor does-not'greatly exceed sublimatio'n'temperature; maintenance inthe-condensing zone ofanhydrousinert conditions; and insuring in'the'condensing zone the absence of gasor Vaponbther than the ZrClivapor'b'eing condensed, in' amount'in. 'excess of'about 5' mol percentofithe' total vapor gas mixture-in the condensing zone.

At'the outset of operation for making thepreferred Zi-Clt startingmaterial for catalyst manufacture/{zirconiurn.tetrachlo'ride, e. g; thepowdery commercialprodnet, is charged into the pot. "The heatingpot,"..condenser and associated pipin are swept of air andmoisture. byinitial flow of an anhydrous inert gas, su'ch,as nitrogen, thru theapparatus for attime interval suflicientrto effect thorough purge. Thevalve 'in 'the nitrogen inlet" line opening into the pot vapor space isclosed. Heating of thexZrCls in the pot and'cor'responding condensationof ZrCh vapor in the condenser are commenced. Shortly thereafter and as,soon, as the condenser exit indicates escapeof Zr-C14 vapor, the valvein the exit pipe is closed or'len just slightly cracked. Subsequently,condensation of 'ZrCl4 vapor in the condenser is effected in an atmos-.phere consisting substantially of. its own vapor.

It has been, found that the type of ZrCLi catalyst manufacture startingmaterial hereindescribed may be produced'by condensation of. ZrCl4 vaporin an atmosphe're which permissibly contains the above indicatedrelatively small amount of inert gas or" vapor other. than ZrClivapor.Thisphase of the present improvementsis important froma practicalviewpoint because it becomes feasible tooperate the entire apparatussystem under a it is. thus possible to use apparatus which is reasonablywell constructed butnot more expensively designed and built for thepurpose of insuring complete exclusion of extraneous gas andvaporinfiltration intothe condensing zone. Nitrogen or other anhydrous inertgas may be permitted tofiow continuously thru the apparatus, and thedesired ZrClisublimate may be obtained provided the rate of flow of gasis controlled so that during a given operation, the. amount of anhydrousinert. gas, e: g. nitrogen, in the vapor spaces of the, apparatusdoes-not exceed about 5 molpercent of the total inertgas-ZrCL; vapormixture present. Such condition can be obtained readily by suitableadjustment of the'nitrogen inlet. valve with respect to, the amounto'f'ZrCls being-vapo'rizedin a given operation.

Ordinarily the desired low positive pressure in the system may bemaintained when the amount of inert anhydrous gas isappreciably lessthan the maximum 5. mol percentindicated. 'IThus,.in-apparatus usuallyemployed, rate of inert gas flow thru the system may be regu: lated, byadjustment of the valve of the inert gas inlet pipe, so that themanometer associated, with the coudenser gas exitpipe indicates a,perceptible plus pressure such as a' positive pressure of about 0.1 to0.5 inches of water, :ordinarilyabout 0.2.inches. Undertheforegoing'circumstances, assuming customary condenser design and acondenser exit pipe not having an, unusually 'low positive pressure. Theresulting advantage is that 4 large cross-section, the amount of inertgas passing through the system usually does not exceed say 2-3 molpercent of the total gas-vapor mixture present. When proceeding in thismanner, theZrCLi starting material used in practice of the invention toform the ZIF4 catalysts is a material which has been formed bycondensing, in a condensing zone, sublimed vapor of zirconiumtetrachloride in an atmosphere of the group consisting of the ZrCl4vapor itself, and a mixture of such vapor, and a quantity of anhydrousinert gas in. amount not more than is needed to maintain the condensingzone under positive pressure high enough to prevent infiltration ofextraneous gas and vapor from the atmosphere, which amount: isordinarily substantially; less than the indicated 5 molpercent maximum.

It is believed that-the efiicacious characteristics of the ZrCl4sublimate produced as above-described are attributable more tothephysical than to'thechemical characteristics of the sublimate. However,.thereare some indications that liquid bottomsin the heating pot mayretain some-substances which, if permitted to -sublime over into thecondenser, woulddeleteriously alfect the desired characteristics of thesublimate. Accord ingly, it is preferred to terminate' the sublimationoperationata-point at which there is left inthe heatingpot a heel of notless than 10% by weight of the original commercial ZrCLi chargedinto-the pot.

The 'neXtphase of operation boadly involves transfer of the ZrCl-isublimate formed in'the condenser to a' reactor inwhich the ZrClr is tobe converted 'by"HF"gassing lCO-lhCZI'F l catalysts of the'invention.More-particularly, thecondensersublimate is gouged, chipped, orotherwise removed from the walls of the condenser coolingsurface, andthe lumps of sublimate thus obtained are granulated and sizedsuitablyfor use in the ZI'Ck- HF gassing reactor. The granulatablecharacteristics of'the-lumps removed from the condenser constitute. anoutstanding practical advantage which will'hereinafter appear.

Granulation'and sizing is a matter-more or less of practicalconsideration, but preferablythe ZrCl4 sublimate lumps should be'granulated and' sized toabout-thru 4 on 12* to 30 mesh. If some. penaltyin the quality of the ultimate ZrF4'catalysts is permissible, as may hethe case insome-circumstances, transfer ofsublimate from the condenserto the ZrCl4--HF gassing reactor may be elfectedunder atmosphericconditions if done as promptlyaspossible and accompanied 'by'practicablyfeasible precautions to minimize contact ofthe ZrCls sublimate in thecondenser with atmospheri air; However, practiceindicates thatconsistent. and best results are obtained Where transfer of the ZrClsublimate from the condenser to the ZrCl4HF gassing reactor is effectedcom:

pletely in an anhydrous, inert gaseous atmosphere such as an atmosphereof. anhydrous nitrogen. Mechanical technique for making such transfer isknown. Thus, it is preferred to make'the ZrCl4. transfer described undercon: ditions such that at the outset of the subsequently de scribedHFfiuorination of theZrCla sublimate, the ZrCl4 sublimate from thecondenser will have been, maintained, during any interval betweencondensationand initiation of fluorination, in an anhydrousinertatmosphere.

Conversion ofthe above describedZrClrtotthe ZrF4 catalysts of theinvention maybe effected for example in, a tubular, nickel reactorprovided with inlet, andv outletconnections for a gas stream, with meansforexternally cooling the reactor as by a blast of air, andwith. anexternally arranged electrical, resistance heater to furnish heat tothereactor as may be neededin; the, laterphase of conversion.

The preferred fluorinating agent employed. is anhydrous gaseoushydrogen. ,fiuoride, although anhydrous. gaseous boron fluoride, (BFzmay also .be used.

Conversion of the ZrCl4 starting: material tothe. ZrFa cata ystscomrises nro i ionpf a reaction zone, pontein:

ing the solid anhydrous zirconium tetrachloride. starting materialdescribed, introducing into the zone a stream of anhydrous gaseousfiuorinating agent, and contacting the same in the reactor with thezirconium tetrachloride. Reaction temperature is maintained in the zoneeffectively high enough to cause substantial reaction between thefiuorinating agent and the zirconium tetrachloride but low enough toprevent, particularly in the early stage of the conversion, appreciablevolatilization of the zirconium tetrachloride. Introduction of the gasstream and contact thereof in the reactor with the zirconiumtetrachloride is continued for a time long enough and in the presence ofsufficient fiuorinating agent to convert at least substantially morethan a major proportion of the tetrachloride to zirconium tetrafiuoridecatalyst.

In instances where the zirconium tetrachloride starting material isdisposed in a bed in a reaction zone, and a gas stream comprisingfiuorinating agent is passed through the bed, the chemical reactionbetween the solid ZI'CLt and the gaseous fiuorinating agent initiallywill be usually concentrated in the upstream portion of the bed andthereafter gradually travel in a downstream direction thru the bed.Inasmuch as the conversion reactions are generally exothermic,particularly in the early stages of conversion, progress of the reactionmay be followed approximately by noting the zone of maximum temperature,i. e. the hot spot in the zirconium tetrachloride bed by means ofsuitably arranged thermocouples. Reaction temperatures may be controlledat levels desired by supplying external cooling in the initial stage andexternal heating in the final stage if required.

Temperatures are maintained suificiently high to bring about reactionbetween the ZrCls and fiuorinating agent, and preferably high enough toeffect ultimate substantially complete conversion of zirconiumtetrachloride to the tetrafiuoride. Although not practically desirable,by limiting the flow of fiuorinating agent or mixing the same with aninert diluent such as nitrogen, the conversion operation throughout maybe effected at temperature of about only a little above roomtemperature, i. e. as low as about 20 C. The conversion reactionsordinarily progress in what may be considered as two fairly distinctphases. In the first, assuming use of HF fiuorinating agent, incoming HPis substantially entirely consumed and the tail gas is substantially allHCl and little or'no HF. End of the first reaction phase andcommencement of the second is indicated by the beginning of anappreciable decrease of HCl content and an appreciable increase of HFcontent in the tail gas, at which time the hot spot will have moved tothe downstream end of the reactor. During the first phase, exothermiccharacteristics are more pronounced and tendency for ZrCl4volatilization is greater. Accordingly, the objective of temperaturecontrol during the first phase is of major importance. It has been foundthat the better overall results are obtained when temperatures duringthe first phase are maintained at a maximum (hot spot) in the range ofabout 30l50 C., usual practice being that hot spot temperature is heldwithin the approximate rangeof 100 C. to 120 C. The desired temperatureregulation may be had by control of HF gas flow thru the reactor,external cooling, or external heating if needed, or by any combinationof these factors.

After completion of the first ZrCl4I-IF reaction phase, tendency ofZrCli toward volatilization decreases markedly. In order to reducereaction time and to obtain quantitative completion of reaction, maximumtemperature may be raised gradually to preferably not higher than about300 C., about 250 C. being the usually preferred maximum temperatureutilized in conversion of the ZICL} to ZrF4. End-point of reaction isindicated by the substantial absence of HCl in the reactor gas.

Time of reaction is that needed, depending upon the particulartemperatures used, to effect substantial conve of Zrch to lFtn. Thu.gassingise i ct d '6 and continued for a period-such that the finalzirconium tetrafiuoride product has a ZrF4 content of at leastordinarily this value being about 98% and higher. In a practicaloperation, HF gassing during first phase may extend over a time intervalfrom 1 to-4V2 hours, and the time needed in the second phase may liewithin the range of 0.5 to 3 /2 hours, time requirement for each phasedepending largelyupon the particular operation at hand and othervariables such as temperature and the desiredrapidity of completion ofthe operation.

An advantage of the herein catalyst preparation method is that theconversion operation may be and normally is carried out at atmosphericpressure..,However, superatmospheric or sub-atmospheric pressures may beutilized if desired, although no particular advantage will ordinarily beobtained thereby. Reaction between fiuorinating agent and zirconiumtetrachloride at the outset may be quite intense, sometimes causing thedevelopment of an excessive amount of heat. In such cases, it may bedesirable to reduce the partial pressure of fiuorinating agentin the gasstream (and simultaneously the reaction intensity) by diluting thefiuorinating agent with a suitable inert gas such as nitrogen. Duringlatter portions of the HF gassing treatment when reaction tends to beless intense, use of inert gas may be discontinued and substantiallypure fiuorinating agent employed.

In catalytic work, size and other physical properties,

e g. resistance to crushing, of pellets or granules of the catalyst isrecognized as being of substantial importance. According to theseimprovements, the zirconium tetrachloride which undergoes HF gassingtreatment does not appreciably change in granule size, distribution orstructural strength. Hence, the zirconium tetrafiuoride catalystgranules advantageously have substantially the same properties, forexample mesh size distribution of the particles and crushing resistance,as the original tetrachloride starting material.

The zirconium tetrafluoride of the invention, although composed of lumpsor other discrete particles of substantial size, when examined even bythe highest powered optical microscopes, appear to be of non-crystallineor amorphous structure. When these amorphous, by ordinary standards,zirconium fluorides are examined using X-ray diffraction technique, suchmaterials are found to be bordering on the amorphous condition, and areextremely small sub-microscopic crystals which are designated inthe artas crystallites. The ZI'F4 catalysts of the invention are catalyticallyuseable size (mesh) increments, e. g. granules or pellets, which'areconstituted of such amorphous zirconium fluoride having crystallitesize. The desired catalytic activity prevails in zirconium fluorides ofcrystallite size of about 400 Angstrom units radius or below. Ascrystallite size decreases below this value, desired catalytic activityincreases and particularly preferred zirconium fluorides include thosehaving crystallite size of about A and below, as determined by X-raydiffraction technique. The foregoing crystallite structures arecharacteristic of zirconium tetrafluoride when made from ZrC'l4 ingeneral as distinguished from other compounds of zirconium. Suchstructure characteristics are in marked contrast to the structurecharacteristics of zirconium tetrafluorides made from zirconiumcompounds other than the zirconium tetra-v chlorides. While zirconiumtetrafiuorides made from compounds other than zirconium tetrachloridesmay consist of lumps or smaller discrete particles, such lumps ofparticles in turn are composed of ZrF4 crystals of relatively largesize, i. e., not less than about 1000 and usually 7 I several thousandAngstrom units radius and above.

The crystallite ZIF4 materials of the invention possess highly activecatalytic properties, and are particularly effective in promotingfiuorinating reactions and may be utilized to catalyze other reactionsinvolving alteration of the halogen (e. g. fluorine) content of organichalogen- 15 ated compounds, .such as disproportionation,hydrohalogenation'and dehydrohalogenation; Gomparative erramples giv'en-=belowshow that the ZrFe catalysts of the invention, in typicalfluorination' operations, efiect greater reaction of HF thanddZrFrcatalysts made from commercial-Z'rCli and also productionofsubstantialquantities of more highly fluorinated products not formedby Z'rFi' catalysts made from commercial -ZrCl4.

There is'nodefinite knowledge-as to the -factors-to' which the 1improved results alforded by-the invention are attributable,Investigationsdo indicate thatwhile ZrF-i may be made by HF gastreatment of-the basic zirconium chloride; i. e. ZrOClzplus water'ofhydration, frompractieal. viewpoint, "such'ZrF sis catalyticall'y'inefiective when usedinthe form of unsupported catalysts. Accordingly,thereappears to be at leastsorne basis forthetheorythat the''sele'ctionof the particular herein-described ZrCl4 starting material together withthe procedural steps of the invention as a whole are such astosubstantially insuretthe absence in the ZrCl4-HF gassing operation ofany-compound of the nature of the ZrOClz hydrate, andcorrespondingabsence in the product of catalyticallyinactive material inthe final ZrFrprod'uct. In connection with possible deleterious eliectof the presenceof'ZrOClz hydrate at least in the manufacture of ZrF4catalyst to: b'e'used in unsupported form, it is noted that the ZICLtstarting material of this invention, prior to HF gas treatment, is inthe form of lumps which may be granulated and thus easily changed tophysical structure readily susceptible to HP gas treatment, and thatsuch structure is retained throughout H-F gassing, with the finishedZrF4 beingin=physical condition directly useable' as a catalyst, allwithout pelleting. Since the ZrCli starting material of th'e inventionisgranular in structure, no pelleting prior to'HF gassing is necessary,and hence the likelihood of the forrn'ation 'of at least some of theZrOClg hydrate during p'elleting is avoided.

The following exemplifies formation of the particular ZrCli startingmaterial employed in praticeof the present imp'rovements, manufacture-ofZrFi catalyst of the invention,.and meet such catalyst in a typicalfluorination: operation, parts and percentages being by weight unlessotherwise noted.

Example 1.-The ZrCl4 sublimation andcondensing apparatus employed was ofthe type which provided for. continuous flow through the system of asmalla'mount ofanhydrous inert gas. Such apparatus comprised ametal-heating p'ot having a valved gas inlet pipe opening into 'thevapor space of the pot, and provided with external heating meansadequate to heat material in the pottotemperature of about 409 C. Thetop of they potwas connected thrua vapor line with a vertically disposedtubular condenser arranged to be externally aircooled. The top of thecondenser was equipped with an overhead gas ofi-take line discharging tothe atmosphere and associated withlamanometer for indicating gaspressure in the gas spaces of the heating pot and condenser,

and-in: the connection piping.

About 700 parts of. commercially-obtainable ZrCl4 in powdered form werecharged into the heating pot. The pot, the ,vapor line connectingthelatter tothe condenser, thecondenser, and the pipe connection betweenthe top of the condenser andthe manometer were completely purged of airand moisture by passing thru the apparatus for-aboutbO minutes a streamof completely anhydrous nitrogen flow of .Which-thru the apparatusto-thegas outlet associated with the manometer being-controlled by the :v-alvein thenitrogen gas'inlet pipe ofthe heating pot. After purging, thevalve in the nitrogen gas inlet was closed down snfficien'tly toprovidefor no more-than a lowpositivepressur'e withinxthe apparatus. TheZrCl4 in the pot wassublimed by maintaining temperature there inof-aboutBOG-350 C. The ZrCh-vapor was condensed in-the air-cooled condenser,operation. being. continued until about 80% of the ZrCl4 charged to thepothad-been vapprized, i. e. -untill.about;2.4 molsof ZrCh. had been potand 'condensen-in small quantity just'enou'gh to main-- tainailow-positiveipressure in the1apparatus, the manometerreadings duringthe .operationi averaging about 0.1

inchr ofliwater; this value bein'gisufficient in this instancetoprevent; zany. infiltration into the apparatusof atmo'sp'heric'.air..andsmoisture and: towminimize thexpresence in theapparatus ofzanyizatmosphereother .thansthatofr ZI'CLL .vapor. The-total: .quantity of nitrogen passed through thetapparatus waslsuchthatduring thecentire' operation. the; nitrogen inthe :system; averagedabout.

I 23 mol percentiotlathe-totaLgas-vapor. mixture'therein.

The freshly sublimed: ZrCLg. was :then chipped: :from thecondenser'walls as'lumps ofcoherent materialwhich" was, granulated andsized-to-aboutl-x l t-mesh. About: 550 (grm) parts ,(400 :cc.) ;of thelatter weretcharged' into. a l I. D. nickel reactor-which wasfullyupacked throughout alength of about 31 inches. In this particularinstan'ce, the transfer of freshly sublimed ZrClt from the condenserto'the reactor was effected-entirely in an anhydrous nitrogen.atmospherewhich was maintained continuouslytrom completionof sublimation uptoinitiationof HF treatment. *The 'foregoingillustrates forma-' tion ofthe*ZrGl4--. starting material utilized in accordance with theinventionto'etfect production ofthe ZrF-i catalyst; thereof.

' The tubular nickel-reactor wasprovided with inlet and outletconnections for a gas-stream, and with means-for externally-coolingthe-reactor by va blast of air. An externally. disposed :electricalresistance: heater was ar range'dto furnish heat to the reactor. whenneeded. Gas- 1 eous, anhydrous fiE initiallyaat a rate. of. about 60parts per hour,-.was.,passed .thruthe reactor while-.maintain-- ing themaximum (hot spot) internal temperature in the reactor. in the rangeofaboutlOO. to not above 150' C. byadjusting the extent of reactorexternal-cooling,- Means were provided to samplethe reactor eilluentgasvto determine theHF or HCl content. Initially thepoint of maximumreaction temperature was substantially at, the upstream end'of thelbedofzirconiu m chloride. Exit gas from'the reactor was periodicallysampled, and after about 4' hours, the evolution of HCl began toslackenand HF began to appear in the reactor exit. By this time, thereactorhot spot-had moved to approximately the: end of the'catalyst bed,and at this stage maximum temperature in the reactorwas about C. Theflow of gaseous anhydrous HF was continued, at a ratev of about '20'pa'rtsperhour, and-internal temperature was. graduallyraisedjto not inexcess of about 240C. so that at th'e'end ofafurther reaction period ofabout 3 hours, thereactorefiiuent' gas contained only HF and wassubstantially free of HCl; At the end of this catalyst manufactureoperation, about 394 parts of zirconium fluoride catalyst; containingabout.98.5% ZrF4 and less than 0.5%

chlorine were obtained. With respect to' granular form andmesh size,theZrF catalyst was the same as at initiation of-HF treatment. X-ray'diifractionpattern of the resulting zirconium fluoride catalystindicated an average crystallite size of about 50 Angstrom units radius,i. e. the crystallite was so srnallas to be indicative of amorphousstructure.

'The followingexemplifies use of the catalyst of the inventionin arepresentative'fiuorination operation. Duringaperiod of about Sphours,2.08 mols of vaporized hexachloroacetone and 10:5 mols of anhydrous HFgas were simultaneouslypassed over 400cc. catalyst made as describedabove, average reaction temperature duringthe run being about 340"" C.,and averagecontact time being about 2 seconds. 6 mols of HClwere-produced, showing that 2.87 mols of HF had reactedpermol ofhexachloroacetone. The exit gas'of'the reactor was handled in knownmanner to recover the organic products which hadthe'following-inrolecular composition? TetrafluorodichloroacetoneCClF2.CO.CClF2 20.2% (B. P. 47 C.) TrifiuorotrichloroacetoneCClFz.CO.CCl2F 38.6% (B. P. 83 C.)

Difluorotetrachloroacetone CClF2.CO.CCl3 and CCl2F.CO.CCl2F 26.1% (B. P.122 C.) Monofluoropentachloroacetone CCl2F.CO.CCl3 17.1% (B. P. 161C.)

The following illustrates manufacture of a ZrF4 catalyst employingcommercial ZrCla as starting material, and use of such catalyst insubstantially the same fluorination operation as outlined above.

Example 2.-About 550 parts of powdered commercial ZrCl4 were chargedinto a tubular nickel reactor similar to the ZrCl4-HF gassing reactor ofExample 1. This powdered ZrCl4 was then gassed with anhydrous HF, andtemperatures and all physical procedure utilized were maintainedsubstantially the same as detailed above in Example 1 with regard tomanufacture of ZrFa catalyst from freshly sublimed ZrCl4. The catalystmade in accordance with the present example from powdered commercialZrCLi contained about 98% Z1'F4 and less than 0.5% chlorine but was inthe form of a powder substantially the same as charged into the reactor.X-ray dilfraction pattern indicated average crystallite size of about 50Angstrom units radius. This powdered ZrF4 product was then compressedinto pellets which were granulated and broken down and sieved. 400 cc.of this catalyst (4 x 14 mesh) were charged into the same fluorinationreactor employed in Example 1. During about 5 hours 2.47 mols ofvaporous hexachloroacetone and 12.2 mols of anhydrous HF gas weresimultaneously passed thru the reactor. 4.88 mols of HCl were formed,indicating that 1.98 mols of HF had reacted per mol ofhexachloroacetone. At this fluorination operation, reactiontemperatures, time of contact, and other corresponding conditions ofoperation of Example 1 were substantially duplicated. The molecularcomposition of the organic products recovered from the procedure ofpresent Example 2 was as follows:

Percent Tetrafluorodichloroacetone CClF2.CO.CClF2 0Trifluorotrichloroacetone CClF2.CO.CCl2F 36.8 DifluorotetrachloroacetoneCClF2.CO.CCla and CCl2F.CO.CCl2F 47.0

Monofluoropentachloroacetone CCl2F.CO.CCl3 16.2

Comparison of the data of Examples 1 and 2 shows that the catalyst ofExample 1 efiected not only a greater reaction of HF, but also resultedin the production of a large quantity of the more highly fluorinatedtetrafluorodichloroacetone, none of which was produced by the catalystemployed in Example 2.

I claim:

1. The process which comprises introducing into a reaction zone solidcomminute anhydrous zirconium tetrachloride starting material,introducing into said zone a gaseous stream of an anhydrous fluorinatingagent of the group consisting of hydrogen fluoride and boron fluoride,and contacting said stream with said tetrachloride; maintainingeffective reaction temperature in said zone high enough to causesubstantial reaction between said agent and said tetrachloride but lowenough to prevent appreciable volatilization of said tetrachloride,continuing introduction of said gas stream and contact thereof with saidtetrachloride for a time suflicient and in the presence of sufficient ofsaid agent to convert a substantial proportion of said tetrachloride toa zirconium tetrafluoride catalyst; said material having been formed asa solid coherent mass and by condensing in a condensing zone thesublimed vapor of the sublimation of zirconium tetrachloride in anatmosphere of the group consisting of (a) said vapor and (b) a mixtureof said vapor and an anhydrous inert gas in amount not in excess ofabout 5 mol percent of said mixture and not more than is needed tomaintain said condensing zone under positive pressure high enough toprevent infiltration of extraneous gas and vapor; and said materialhaving been maintained, during comminution and the stage betweencondensation and initiation of fluorination, in an anhydrous inertatmosphere.

2. The process of claim 1 in which the said material is formed bycondensing in a condensing zone the sublimed vapor of zirconiumtetrafluoride in an atmosphere consisting substantially of said vapor.

3. The process which comprises introducing into a reaction zone solidcomminuted anhydrous zirconium tetrachloride starting material,introducing into said zone a gaseous stream of an anhydrous fluorinatingagent of the group consisting of hydrogen fluoride and boron fluoride,and contacting said stream with said tetrachloride; initiallymaintaining said starting material at maximum temperature in the rangeof about 30-150 C. at least until the reaction zone exit gas showsappreciable decrease of HCl content and appreciable increase of HFcontent, thereafter continuing fluorination at higher temperature not inexcess of about 300 C. until said exit gas contains substantially no HCland there is formed a zirconium tetrafluoride catalyst containing atleast ZrF4; said starting material having been formed as a solidcoherent mass and by condensing in a condensing zone the sublimed vaporof the sublimation of zirconium tetrachloride in an atmosphere of thegroup consisting of (a) said vapor and (b) a mixture of said vapor andan anhydrous inert gas in amount not in excess of about 5' mol percentof said mixture and not more than is needed to maintain said condensingzone under positive pressure high enough to prevent infiltration ofextraneous gas and vapor; and said material having been maintained,during communition and the stage between condensation and initiation offluorination, in an anhydrous inert atmosphere.

4. The process which comprises introducing into a reaction zone solidcomminuted anhydrous zirconium tetrachloride starting material,introducing into said zone a gaseous stream of an anhydrous fluorinatingagent of the group consisting of hydrogen fluoride and boron fluoride,and contacting said stream with said tetrachloride; initiallymaintaining said starting material at maximum temperature in the rangeof about 30150 C. at least until the reaction zone exit gas showsappreciable decrease of HCl content and appreciable increase of HFcontent, thereafter continuing fluorination at higher temperature not inexcess of about 300 C. until said exit gas contains substantially no HCland there is formed a zirconium tetrafluoride catalyst containing atleast 95% ZrFa; said starting material having been formed as a solidcoherent mass and by condensing in a condensing zone the sublimed vaporof the sublimation of zirconium tetrachloride in an atmosphere of thegroup consisting of (a) said vapor and (b) a mixture of said vapor andan anhydrous inert gas in amount not in excess of about 5 mol percent ofsaid mixture and not more than is needed to maintain said condensingzone under positive pressure high enough to prevent infiltration ofextraneous gas and vapor.

References Cited in the file of this patent UNITED STATES PATENTS1,927,108 Zimmermann Sept. 19, 1933 2,602,725 Wilhelm et a1. July 8,1952 2,618,531 Lindblad Nov. 18, 1952 2,695,213 Fernelius Nov. 23, 1954OTHER REFERENCES I. W. Mellor: vol. 7, 1927 Ed. Inorg. and TheoreticalChem. page 144. Longmans, Green and Co., N. Y.

1. THE PROCESS WHICH COMPRISES INTRODUCING INTO A REACTION ZONE SOLIDCOMMINUTE ANHYDROUS ZIRCONIUM TETRACHLORIDE STATING MATERIAL,INTRODUCING INTO SAID ZONE A GASEOUS STREAM OF AN ANHYDROUS FLUORINATINGAGENT OF THE GROUP CONSISTING OF HYDROGEN FLUORIDE AND BORON FLUORIDE,AND CONTACTING SAID STREAM WITH SAID TETRACHLORIDE; MAINTAININGEFFECTIVE REACTION TEMPERTATURE IN SAID ZONE HIGH ENOUGH TO CAUSESUBSTANTIAL REACTION BETWEEN SAID AGENT AND SAID TETRACHLORIDE BUT LOWENOUGH TO PREVENT APPRECIABLE VOLATILIZATION OF SAID TETRACHLORIDE,CONTINUING INTRODUCTION OF SAID GAS STREAM AND CONTACT THEREOF WITH SAIDTETRACHLORIDE FOR A TIME SUFFICIENT AND IN THE PRESENCE OF SUFFICIENT OFSAID AGENT TO CONVERT A SUBSTANTIAL PROPORTION OF SAID TETRACHLORIDE TOA ZIRCONIUM TETRAFLUORIDE CATAYLST; SAID MATERIAL HAVING BEEN FORMED ASA SOLID COHERENT MASS AND BY CONDENSING IN A CONDENSING ZONE THESUBLIMED VAPOR OF THE SUBLIMATION OF ZIRCONIUM TETRACHLORIDE IN ANATMOSPHERE OF THE GROUP CONSISTING OF (A) SAID VAPOR AND (B) A MIXTUREOF SAID VAPOR AND AN ANHYDROUS INERT GAS IN AMOUNT NOT IN EXCESS OFABOUT 5 MOL PERCENT OF SAID MIXTURE AND NOT MORE THAN IS NEEDED TOMAINTAIN SAID CONDENSING ZONE UNDER POSITIVE PRESSURE HIGH ENOUGH TOPREVENT INFILTRATION OF EXTRANEOUS GAS AND VAPOR; AND SIAD MATERIALHAVING BEEN MAINTAINED DURING COMMINUTION AND THE STAGE BETWEENCONDENSATION AND INITIATION OF FLUORINATION, IN AN ANHYDROUS INERTATMOSPHERE.